Triathlete Recommendation Needed

I started my triathlete training last year, and will be going for my first attempt coming year.
Triathletes want different set of information in front of them when they are on the go!
1. For swimmers (depending on Open Water and Pool Swimming), you will be looking forward to your swim speed, swim cadence, distance travelled, stroke count, stroke style, and time.
2. For runners, data like speed, distance, elevation, run cadence, altitude, temperature and time shall be useful.
3. And for bikers, you can have data stats like bike speed, distance, pedaling effort, elevation, gradient and time.
My trainer recommended buying sports watch that will display all these data metrics. What do you say in this regard?!